Currently, very high resolution flat-panel display devices are being developed and brought to market. One example is liquid crystal display (LCD) devices with 4K×2K resolution (2160 lines and 4096 pixels/line). Such display devices are exceeding the highest spatial resolution of video content commonly available, namely 1080 p high definition video (1080 lines and 1920 pixels/line). Thus, it may be desirable to use image and video upscaling or spatial format conversion methods in such display devices.
Recent display devices may also be capable of and benefit from higher frame rates or increased temporal resolution, such as 50, 60, 72, 96 or 120 frames per second. Again, such very high frame rates may exceed the highest frame rate of video content commonly available (24, 25, 30, 50 or 60 frames per second). This highlights the usefulness of temporal video upscaling or temporal video frame rate conversion methods.
Generally, the goals in achieving video interpolation and reconstruction are to enhance or increase the resolution of the input video in a manner that is visually pleasing and artifact-free. Common visual artifacts that may occur in spatial upscaling are edge jaggyness, ringing on edge contours, blurring of edges and blurring of texture detail. Common visual artifacts that may occur in temporal upscaling are motion blur, judder, temporal instability and other motion artifacts. In addition, the input video often may already contain artifacts, for example due to coding and compression or due to other processing stages generally preceding the final processing for display. Therefore, another goal is to avoid amplifying such artifacts in the input signal, and possibly to remove such artifacts.
Due to changing viewing conditions (e.g., closer viewing distances, darker surroundings), as well as incorporation of new display technologies (e.g., larger screens, higher brightness, wider color gamut) in modern flat-panel display devices, any artifacts in the input video as well as any additional artifacts that may be introduced by the scaling or conversion method used are becoming more visible than in the past. This highlights the usefulness of high-quality scaling and format conversion methods as well as other video processing methods, such as noise suppression.